Magnetic lifting device for a cellular sample treatment apparatus

ABSTRACT

A magnetic lifting device for lifting a stack of specimen holders out of one tube and lowering them into another tube is disclosed. The device avoids the necessity of manual handling of the stack. In the device there are a number of stack holding tubes, each one open at the top, positioned in a circle about a vertical axis of a rotatable carousel. An indexing system rotates the carousel to selectively place one of the stack holding tubes in a treatment position. The improvement comprises a magnetizable member attached to the top of the stack of sample holders, a transfer tube having a bottom opening positioned to mate on top of the stack holding tube to hold the magnetizable member in a magnetic field, a device to raise and lower the magnetic coil about the transfer tube to raise and lower the magnetic coil about the transfer tube to raise the stack into the transfer tube allowing the carousel to be rotated, and lower the stack into another stack holding tube.

The present invention relates to an apparatus for treating animal andvegetable tissue samples for inspection under an electron microscope.More specifically, the present invention relates to a novel magneticlifting device which raises samples contained in a stack of sampleholders from a lower tube to an upper tube.

In the preparation of animal and vegetable tissue samples forexamination under an electron microscope, it is necessary to treat thetissue sample and this is done by removing the water in a series ofchemical dehydration steps and then replacing the water removed from thetissue sample with an epoxy resin. The addition of an epoxy resinhardens the sample so that it can then be sliced into thin sectionssuitable for examination under the microscope.

The process of replacing water in a tissue sample with epoxy is acomplex process which includes placing the samples into corrosivechemicals and/or buffering solutions. The tissue sample is placed in anumber of different solutions, in a series of steps involving heatingand cooling which can take from three to four hours. If this process isdone manually then it requires almost constant attention which consumesconsiderable operator time. It is most important that these steps befollowed in the correct sequence to ensure that the tissue is notdamaged by removal of the water and replacement with epoxy.

Automated processes and devices have been made to treat animal andvegetable tissue samples. In some known devices corrosive liquids arepumped into tubes containing tissue samples. It has been found that thepumping of these corrosive liquids is not only dangerous but alsowasteful, because after the pumping step the fluids have to bedischarged. Furthermore, the tubes and pumps through which the liquidpasses tend to corrode and, therefore, must be replaced frequently.

It is an object of the present invention to provide an apparatus forpreparing animal and vegetable tissue samples for inspection under anelectron microscope which is completely automated and can be preset tostart while unattended. In this way, tissue samples which are needed inthe morning can be left in the device which is programmed to starttreatment four or five hours before the operator comes into thelaboratory, so that the samples are ready for being sliced into suitablespecimens for inspection. Furthermore, it is another object of theinvention to provide an apparatus which does not have a series of tubesand pumps to move the chemicals to the sample, but rather which isarranged to move the tissue samples from one container to anothercontaining the necessary chemicals. The apparatus moves the tissuesamples to the chemicals rather than the chemicals to the samples.

The present invention provides in an apparatus for treating samples ofcellular materials wherein the samples are contained in a plurality ofsample holders joined together to form a stack, the apparatus includinga plurality of stack holding tubes, each one open at the top, positionedin a circle about a vertical axis of a rotatable carousel, drive meansfor rotating the carousel to selectively place one of the stack holdingtubes in a treatment position, the improvement comprising a magnetizablemember attached to the top of the stack of sample holders, a transfertube having a bottom opening positioned to mate on top of the stackholding tube in the treatment position, a magnetic coil about thetransfer tube to hold the magnetizable member in a magnetic field, meansto raise and lower the magnetic coil about the transfer tube to raisethe stack into the transfer tube allowing the carousel to be rotated,and lower the stack into another stack holding tube.

In other embodiments of the invention, there is a second magnetic coiladjacent the magnetic coil about the transfer tube, with a means topulse electric power to one of the magnetic coils such that a vibratoryeffect is transferred to the stack. In another embodiment a top magneticcoil is provided located at the top of the transfer tube to hold thestack in the top position in the transfer tube. In yet a furtherembodiment, the means to lower and raise the magnetic coil about thetransfer tube raises the transfer tube from the stack holding tube inthe treatment position on the carousel.

The invention also provides in another embodiment a linear movementmeans for moving the carousel into at least three positions representinga rotating position, a cap removal position and the treatment position.A drip tray may be provided positioned under the transfer tube, the driptray mounted on a spring loaded arm adapted to allow the drip tray tomove aside when the carousel is moved linearly to the treatmentposition. A heating and cooling means may be positioned to heat and coolthe stack holding tube in the treatment position.

In drawings which illustrate embodiments of the invention,

FIG. 1 is a side elevational view of one embodiment of an aparatus fortreating samples of cellular materials.

FIG. 2 is a top sectional view take at line 2--2 of FIG. 1,

FIG. 3 is a front end view of the apparatus shown in FIG. 1,

FIG. 4 is a sectional view taken at line 4--4 of FIG. 3 showing a stackholding tube in the treatment position.

FIG. 4A is a detailed sectional view taken at line 4A--4A of FIG. 4showing the fork member for engaging a cap,

FIG. 5 is an isometric view of a control panel for operating theapparatus of the present invention,

FIG. 6 is a flow chart of the start sequence,

FIG. 7 is a flow chart of the chemical change sequence.

Referring now to the drawings, an apparatus for treating samples ofcellular material is shown in FIGS. 1, 2 and 3 having a base plate 10 onwhich is mounted a carousel 11 with mechanisms to rotate the carousel,and move the carousel in a linear direction. The carousel has a topplate 12 and a bottom plate 13 and a plurality of holes 14 in bothplates 12, 13 located in a circle about a rotating axis 15. The holes 14hold disposable plastic stack holding tubes 16 for a stack of sampleholders. In one particular embodiment, there are twenty-two holes 14 tohold plastic stack holding tubes. The stack holding tubes 16 contain thedifferent chemicals for the treatment process.

The carousel 11 is supported from a carriage block 20 which moveslinearly backwards and forwards on two shafts 21, one a screw shaft, andthe other a hardened smooth shaft. The shafts are supported by sidesupport plates 22, mounted on the base plate 10. The carousel 11 has arotate motor 23 mounted by means of a bracket 24 on the carriage block20. The rotate motor 23 is a stepping motor and has a belt drive drivinga pulley wheel 25 attached to the underside of the carousel 11 to rotatethe carousel 11. Index pins 26 extend down from the pulley wheel 25 andare arranged to interrupt an integral light emitter sensor 27 positionedon the carriage block 20 to index the carousel 11 from one hole 14 tothe next.

The linear movement of the carousel is provided by a linear motor 28which through a pulley drive 29 rotates the screw shaft 21 moving thecarriage block 20 backwards and forwards. As illustrated in FIG. 1, thecarriage block 20 may be positioned so that a stack holding tube 16 isin one of three positions, position A being the carousel rotationposition, position B being the cap removal position and position C beingthe treatment position. The linear motor 28 is a stepping motor and apositioning pin 30 extending from the carriage block 20 is arranged tointerrupt three integral light emitter sensors 31 positioned on the baseplate 10 representing positions A, B and C.

A top transfer tube 32 having a lower flange 33 to engage and snap ontoa stack holding tube 16 in the treatment position C on the carousel 11is positioned above the carousel 11. As seen in more detail in FIG. 4,the transfer tube 32, which is preferably made of polyethylene or othersuitable material, is connected at its top by means of a screw thread 34to the core of a top hold magnetic coil 35 and has a shaft 36 extendingfrom the top coil 35 passing through a bushing 37 in a top support plate38. The top support plate 38 is held upright by two posts 39 which areattached to the base plate 10. Two magnetic transfer coils 40, 41surround the top transfer tube 32 and are connected to a travellermember 42 which fits over the two posts 39 and is arranged to slide upand down on these posts 39. A drive shaft 43 having a screw threadthereon parallel to the posts 39 has an internally threaded block 44 inthe traveller member 42, thus rotation of the shaft 43 moves thetraveller member 42 up and down so that the magnetic transfer coils 40,41 move up and down the top transfer tube 32. The threaded shaft 43 isrotated by an up and down motor 45 mounted on the top support plate 38and driven through a pulley drive 46 to position the traveller member 42and thus the magnetic coils 40, 41 about the top transfer tube 32. Theup and down motor 45 is a stepping motor, and as shown in FIG. 4, apositioning pin 46 on the traveller member 42 interrupts two integrallight emitter sensors controlling the top and bottom positions of thetraveller member 42.

When the magnetic coils 40, 41 reach the top of the top transfer tube32, the top magnetic coil 35 and the shaft 36 is pushed upwards so thatthe shaft 36 slides in bushing 37 and the top tube 32 is raised abovethe stack holding tube 16 in the carousel 11.

The stack holding tube 16 generally has a cap 48 over the top of thestack holding tube 16 to seal it when not in treatment position. The cap48 has a top button 49 which may be engaged by a fork member 50 attachedto the travelling member 42 at the top of the magnetic transfer coils40, 41. The fork member 50 as shown in FIG. 4A has a slot 51 to engagewith the top button 49 on the cap 48. The cap 48 has a flange 52 similarto the flange 33 on the bottom of the top transfer tube 32, whichengages and snaps onto the top of a stack holding tube 16.

At the bottom of each stack holding tube 16 is a lower button 53 whichengages with a hold down fork 54 fixed to the frame of the device. Thehold down fork 54 holds the stack holding tube 16 when in position B andC so the tube 16 is held down when the cap 48 is removed and when thetop transfer tube 32 is removed.

In the treatment position C below the top tube 30 is a heating andcooling jacket 55A having a contoured groove to support a stack holdingtube 16. A second heating and cooling jacket 55B, also having acontoured groove is located adjacent the first jacket 55A so that astack holding tube in a preprocess position can be heated or cooled asrequested. The temperatures of the two jackets, 55A and 55B, arecontrolled independently by closed loop systems monitoring temperaturesensors (not shown) in the two jackets, 55A and 55B. Cooling coils areincluded in the support members 56 which are attached by clamps 57 tothe posts 39. Connections 58 are provided for cooling water to thecooling coils. Thus a stack holding tube 16 can be preheated orprecooled in the preprocess position before being moved to the treatmentposition C. A drip tray 60 is provided to rest underneath the top tube30 when the carousel 11 is not moved so that there is a stack holdingtube 16 in the treatment position C. The drip tray 60 has a springloaded arm 61 and when the carousel 11 is moved so that there is a stackholding tube 16 in the treatment position C, the drip tray 60 is pushedto one side.

Tissue samples 70 to be treated are shown in FIG. 4, each sitting on astainless steel screen 71 of an individual sample holder 72, made ofplastic material and arranged to snap together into a stack of sampleholders 72. At the top of the stack is a magnetizable member 73 made ofmagnetic stainless steel with a hole 74 in the centre thereof forventing purposes. In one embodiment up to thirteen individual sampleholders 72 may be snapped together to form a stack and joined to the topmagnetizable member 73. Each holder 72 can contain at least one tissuesample 70 to be treated.

In operation, the sample holders 72 are assembled one by one with thetissue samples 70 therein resting on the stainless steel screens 71between the holders 72. As the holders 72 are assembled, they are filledwith liquid solution to remove air from within the stack specimenholders 72. It is important that the tissue samples are not allowed todry out, as a dried out sample is not suitable for electron microscopeexamination. The stack of holders 72 with the top magnetizable member 73joined together is then moved into a first stack holding tube 16, a cap48 positioned on the tube 16 which is then placed in the carousel 11.Other stack holding tubes 16 also on the carousel are filled with thenecessary liquids for removing water and treating the specimens 70.

The carousel 11 is rotated until the tube 16 holding the stack ofspecimen holders 72 is lined up in position A. The travel member 42 isbrought down to a cap engaging height by the up and down motor 45 sothat the fork member 50 is positioned for the slot 51 to engage with thebutton 49 on the cap 48. The carousel 11 is then moved linearly by thelinear motor 28 so the tube 16 is moved to position B when the slot 51of the fork member 50 engages with the cap 48. The up and down motor 45for travelling member 42 then raises the cap 48 off the stack holdingtube 16 in the carousel 11, the tube hold down fork 54 anchoring thestack holding tube 16 in the carousel. The carousel 11 is then movedlinearly by the linear motor 28 so the tube 16 is moved to position Cpressing the tube 16 into the heating and cooling jacket 55A, and the upand down motor 45 for the travelling member 42 lowers the top transfertube 32 onto the top of the stack holding tube 16 and snaps the twotubes together. The two magnet transfer coils 40, 41 are then activated.One coil 40 is on all the time, the second coil 41 pulses which producesa vibratory effect on the magnetizable member 73 and consequently on thestack of holders 72 with the tissue samples 70 therein. The intensity ofvibration can be varied as desired for different liquids. The travelmember 42 is slowly raised by the up and down motor 45 and the magneticcoils 40, 41 produce a magnetic field to hold the magnetizable member 73so that it moves upwards and brings the stack of holders 72 with it. Thevibratory effect breaks up the surface tension of liquid within thestack so the liquid remains in the stack holding tube 16. When the coils40, 41 reach the top of the top transfer tube 32, the travelling member42 continues upwards raising the top transfer tube 32 so it disengagesfrom the stack holding tube 16 in the carousel 11. The top holding coil35 is then turned on and the two moving coils 40, 41 are turned off sothat the magnetizable member 73 is held in the magnetic field of the topholding coil 35 and the stack of holders 72 remains at the top of thetop transfer tube 32. The linear motor 28 then moves the carousel 11back to position B. The travel member 42 is lowered by the up and downmotor 45 so that the cap 48 is replaced on the stack holding tube 16.The linear motor 28 then moves the carousel 11 back to position A andthe rotate motor 23 rotates the carousel 11 by one step. A furthersequence occurs and another tube is moved forward. The cap 48 may beremoved in the same manner and the tube is then placed in the treatmentposition C. The stack of holders 72 is dropped into the new tube 16 byturning off the top holding coil. The agitation of the stack of holders72 in the new tube is achieved by pulsing the magnetic transfer coils40, 41 according to a predetermined rate and intensity. The heating andcooling jackets 55A and 55B may be utilized for predetermined timeperiods in the treatment position and in the pretreatment positionaccording to a particular program.

When the linear motor 28 moves the carousel 11 away from the treatmentposition, a drip tray 60 swings into place on a spring loaded arm 61 tocatch any drips of liquid which may drop from the stack of holders 72 inthe top transfer tube 32. When the treatment sequence is finished, andafter the stack of holders 72 has been returned to the original stackholding tube 16 the linear motor 28 moves the carousel 11 to position A,and the stack of holders 72 may be removed from the stack holding tube16, dismantled, and the specimens 70 taken for further processing. Allthe movements of the three motors, rotating the carousel, linearlymoving the carousel and raising and lowering the transfer tube 32 arelimited by optical sensors in the embodiment shown wherein a pininterrupts a beam of light. It will be apparent to those skilled in theart that other types of limit switches can control the indexing andlength of movements.

An exhaust fan may be included with the apparatus with the modular unithaving an enclosure surrounding it. The exhaust fan removing any toxicor obnoxious fumes.

All the stack holding tubes used to hold the stack of holders 72 and thedifferent chemicals may be thrown out after each preparation run.Furthermore, the top transfer tube 32 is also thrown out after each runso there is no need to clean tubes or containers, all items touched bythe chemicals are disposable.

The mechanical function of the apparatus is controlled by a separatecontroller contained in a separate container. One controller may controlup to eight different mechanical modules, all programmed to performdifferent or similar steps at the same time or at different times. Thusthe system is a modular system allowing up to eight separate modules.

The push button controls for a mechanical module are indicated in FIG. 5where the first push button, labelled "index", indexes the carousel torotate one tube position for each depression. The "load" button returnsthe carousel so a first tube hole is always at the same positionopposite the start switch. The "enable" button is a prerequisite beforepressing the "start" button and when the "start" button is depressed,the first tube hole is rotated in the carousel, a tube uncapped and thenpressed into the temperature jacket awaiting a program to be executedfrom the controller, referred to as the central processing unit (CPU).The "D start" button is the same function as the "start" button butincludes a programmed time delay. The "reset" button stops whatever stepis in process and returns the first tube hole to the start position. The"pause" button suspends the timed sequence occuring, and the "power on"is an indicator light.

The flow sheet for the start sequence from the central processing unit(CPU) is shown in FIG. 6.

The sequence of steps is as follows:

Program central processing unit (CPU).

Assemble specimen stack with the tissues to be processed.

Top off stack with magnetic stainless steel actuator.

Insert stack assembly into stack holding tube and place into first oftwenty two tube holes in carousel opposite start switch.

Fill required number of tubes with appropriate chemicals.

Insert capped tubes containing chemicals in sequence to be used incarousel.

Push "enable" switch.

Push "start" switch.

CPU recognizes a valid start sequence.

A. CPU rotates carousel to move the specimen stack holding tube oppositethe processing station.

B. CPU lowers transfer coil assembly and attached cap removal fork.

C. CPU moves carousel inwards to engage tube cap and cap removal fork.

D. CPU raises the transfer coil assembly with the cap removal forkretaining the cap and thereby opens the specimen stack holding tube.

E. CPU moves carousel into the process station pressing the tube intothe processing temperature control block.

F. CPU lowers the transfer coil assembly until the transfer tube and theopen specimen stack holding tube are sealed together.

G. CPU blanks CPU display to prompt user to enter the two digit programnumber to be executed.

User enters two digit number program.

CPU turns on "start" switch lamp. Begins processing according to time,temperature and agitation parameters of the first step of the particularprogram.

The flow sheet for the change chemical sequence is shown in FIG. 7. Thesequence of steps is as follows:

CPU times out step in process.

CPU displays next step and begins change sequence.

A. CPU turns on the transfer electromagnetical coils top and bottom andpicks up the specimen stack.

B. CPU raises the transfer coil assembly and the magnetically heldspecimen stack.

C. CPU shakes off excess chemicals in the specimen stack by turning thetop magnetic transfer coil 40 on and off while keeping the bottomtransfer coil 41 on continuously.

D. CPU turns on the hold electromagnetical coil when the stack andtransfer assembly have cleared the tube and turns off the transfer coilstop and bottom.

E. CPU moves the carousel out of the process station to the cap station.

F. CPU lowers the transfer coil assembly with the tube cap in the capfork until the cap and the open tube are sealed together.

G. CPU moves the carousel back to the rotate position.

H. CPU rotates carousel so next tube with chemicals is opposite theprocessing station.

I. CPU moves the carousel inwards to engage the tube cap and cap removalfork.

J. CPU raises the transfer coil assembly with the cap removal forkretaining the cap, and thereby opens the tube.

K. CPU moves the carousel into the process station pressing the tubeinto the processing temperature control block.

L. CPU lowers the transfer coil assembly until the transfer tube and theopen tube are sealed together.

M. CPU turns off the hold coil allowing the specimen stack to fall intothe new chemical containing tube.

N. CPU begins processing according to time, temperature and agitationparameters of the new step of the particular program.

Various changes may be made to the different elements shown in theapparatus without departing from the scope of the present inventionwhich is limited only by the following claims.

The embodiments of the invention in which an exclusive property orpriviledge is claimed are defined as follows:
 1. In an apparatus fortreating samples of cellular materials wherein the samples are containedin a plurality of sample holders joined together to form a stack,theapparatus including a plurality of stack holding tubes, each one open atthe top, positioned in a circle about a vertical axis of a rotatablecarousel, drive means for rotating the carousel to selectively place oneof the stack holding tubes in a treatment position, the improvementcomprising a magnetizable member attached to the top of the stack ofsample holders, a transfer tube having a bottom opening positioned tomate on top of the stack holding tube in the treatment position, amagnetic coil about the transfer tube to hold the magnetizable member ina magnetic field, means to raise and lower the magnetic coil about thetransfer tube to raise the stack into the transfer tube allowing thecarousel to be rotated, and lower the stack into another stack holdingtube
 2. The apparatus according to claim 1 including a second magneticcoil adjacent to the magnetic coil about the transfer tube, means topulse electrical power to one of the magnetic coils such that avibratory effect is transferred to the stack
 3. The apparatus accordingto claim 1 including a top magnetic coil located at the top of thetransfer tube to hold the stack in the top position in the top tube. 4.The apparatus according to claim 1 wherein the means to raise and lowerthe magnetic coil about the transfer tube raises the transfer tube fromthe stack holding tube in the treatment position on the carousel.
 5. Theapparatus according to claim 1 including linear movement means formoving the carousel into at least three positions representing arotating position, a cap removal position and the treatment position. 6.The apparatus according to claim 5 including a drip tray positionedunder the transfer tube, the drip tray mounted on a spring loaded armadapted to allow the drip tray to move aside when the carousel is movedlinearly to the treatment position.
 7. The apparatus according to claim1 including a heating and cooling means positioned to heat and cool thestack holding tube in the treatment position.